This invention is in the area of the prevention, diagnosis and treatment of autoimmune diseases, especially systemic lupus erythematosus.
The United States government has rights in this invention by virtue of grants from the National Institutes of Health and the Veteran's Administration.
Systemic lupus erythematosus (SLE) is similar to many other disorders in which autoantibodies are found and thought to be important in etiology and pathogenesis. SLE can be grouped with those diseases that commonly have autoantibodies present but for whom a central role of autoantibody in pathogenesis leading to clinical expression has yet to be fully established or accepted. Other such diseases include Sjogren's syndrome, rheumatoid arthritis, juvenile onset diabetes mellitus, primary biliary cirrhosis, Wegener's granulomatosis, inflammatory bowel disease, and many others.
Typically, autoimmune diseases present with a wide array of symptoms and clinical signs. The production of circulating autoantibodies to ribonucleoprotein complexes (RNPs) is a unifying characteristic of some of the rheumatic autoimmune diseases. The most common antigens in SLE and closely related disorders include: Ro/SSA, La/SSB, nRNP and Sin. Initially, these antibodies were found using double immunodiffusion, but more recently sensitive solid phase assays have been developed to quantitate the autoantibodies. The Ro/SSA RNA-protein particle has been found to be a constituent of all human cells evaluated to date. Approximately half of Sjogren's syndrome and systemic lupus erythematosus (SLE) patients have anti-Ro/SSA precipitins. Approximately 75% of patients with subacute cutaneous lupus erythematosus or complement component C2 deficiency with SLE have anti-Ro/SSA precipitins. Over 80% of mothers of newborns with neonatal lupus dermatitis or complete congenital heart block have this autoantibody. As many as 5% of patients with rheumatoid arthritis, polymyositis, and progressive systemic sclerosis have anti-Ro/SSA, as reported by R. M. Bernstein, et al., Mol, Biol. Med. 2:105-120 (1984); and J. B. Harley and K. K. Gaither, Autoantibodies. In Rheumatic Disease Clinics of North American: Systemic Lupus Erythematosus 14:1, 43-56 (1988).
It has been an issue of intensive debate as to whether the many autoantibodies found in systemic lupus erythematosis and related diseases represent an antigen specific or a polyclonal, antigen non-specific response. Evidence that autoantibodies are important in the expression of SLE and related syndromes is convincing. Specific depletion in a heart block neonate (Harley, J. B., et al., Arthritis Rheum.28:1321-1325 (1985)) and specific anti-Ro/SSA immunoglobin deposition in human skin (Lee, L. A., et al., J. Clin. Invest. 83:1556-1562 (1989)) have been demonstrated. Specific concentration of anti-Ro/SSA has been shown in the immunoglobulin of renal eluates from kidneys affected by lupus nephritis (Maddison, P. J. and Reichlin, M. Arthritis Rheum. 22:858-863 (1979)). Anti-Ro/SSA has been found to be specifically concentrated in a parotid gland of a patient with Sjogren's syndrome and primary biliary cirrhosis (Penner, E. and Reichlin, M. Arthritis Rheum. 25:1250-1253 (1982)). Observations that infants with transplacentally acquired maternal IgG develop neonatal lupus dermatitis and/or complete congenital heart block (Harley, J. B. and Gaither, K. K.: Autoantibodies. In Rheumatic Disease Clinics of North America: Systemic Lupus Erythematosus 14:1,43-56 (1988)) strongly suggests that maternal autoantibody (anti-Ro/SSA or anti-La/SSB) transported across the placenta is a critical component required, but not sufficient, for these clinical problems.
It has also been shown that some normal individuals have low levels of anti-Ro/SSA, that some normal family members of SLE patients have anti-Ro/SSA, and that 1% of normal pregnant women, and 0.1% of a cohort of hospitalized patients have precipitating levels of this autoantibody K. K. Gaither, et al., J. Clin. Invest. 79:841-846 (1987); T. J. A. Lehman, et al., J. Rheumatol. 11:644-647 (1987); M. Calmes and B. A. Bartholomew, J. Clin. Pathol. 38:73-75 (1985); P. J. Maddison, et al., J. Rheumatol. 5:407-411 (1978)). Even if the anti-Ro/SSA autoantibody is not pathogenic, the concentrations of anti-Ro/SSA autoantibody achieved by patients can be extraordinary, and is commonly higher than 1 mg/ml of specific anti-Ro/SSA immunoglobulin (K. K. Gaither and J. B. Harley, Prot. Biol. Fluids Proc. Colloq. 33:413-416 (1985); J. B. Harley, et al., Arthritis Rhuem. 29:196-206 (1986)). The immune system derangement leading to this specific overproduction of anti-Ro/SSA is not apparent but is likely to reflect a fundamental mechanism related to the immunopathogenesis of the related diseases.
The Ro/SSA family of proteins has now been shown to have several molecular forms which are operationally defined by the molecular weight of the antigen identified. A major form has an apparent molecular weight of 60 kiloDaltons (kD). This protein is associated with one of four hY RNAs. Recently, two additional proteins bound by anti-Ro/SSA sera have been identified by M. D. Rader, et al., J. Clin. Invest. 83:1556-1562 (1989), with molecular weights of 52 kD and 54 kD. A 48 kD protein, calmodulin, has been identified as being bound by anti-Ro/SSA sera (McCauliffe, et al., J. Clin. Invest. 85:1379-1391 (1990)). The La/SSB protein, a 48 kD peptide, as described by J. C. Chambers and J. D. Keene, Proc. Natl. Acad. Sci. USA 82:2115-2119 (1985), is also a member of this group of autoantibodies, and binds small RNAs with a polyuridine terminus, as reported by J. E. Stephano, Cell 36:145-154 (1984). La/SSB is bound by a third of the anti-Ro/SSA precipitin positive sera. Anti-Ro/SSA autoimmune sera and heteroimmune rabbit sera have been used to demonstrate different specificities for lymphocyte Ro/SSA and red blood cell Ro/SSA. While several specificities have been noted for the Ro/SSA RNP, very little information exists defining the specific epitopes involved in the autoimmune response.
It is therefore an object of the present invention to provide methods for identifying immunogens, and the specific epitopes and sequences encoding the epitopes, which elicit the production of an autoimmune response involving antigens or autoantigens that are bound by immunoglobulin, antigen-specific B cell surface receptor molecules, or the antigen-specific T cell receptor.
It is a further object of the present invention to provide assays and diagnostic reagents for identifying individuals previously exposed to a particular immunogen or expressing these autoantibodies, or the epitopes (or their immune equivalent) eliciting production of the autoantibodies.
It is a still further object of the present invention to provide methods and compositions for identifying and treating autoimmune disorders, including such diverse diseases as Sjogren's syndrome, rheumatoid arthritis, juvenile onset diabetes mellitus, primary biliary cirrhosis, Wegener's granulomatosis, inflammatory bowel disease, potentially autoimmune disorders, or any other disease having immune manifestations.
It is a still further object of the present invention to provide a procedure to determine the immunologic origin of autoimmune manifestations of diseases.
It is another object of the present invention to provide an animal model expressing human autoantibodies for screening therapeutics.
It is yet another object of the present invention to provide a procedure to determine the origin of selected manifestations of diseases of known etiology.